Long Span Beam to Support Exterior Wall

[EV11]

Hello,

I am working on a residential project for a client that currently has a 24’ x 30’ garage. The garage is in good condition, and he would like to add an addition. He would like to remove half of the existing garage, and to the remaining 12’ x 30’ section – add a new addition.
The new addition would be 30’ x 30’, and it would be higher than the existing garage structure. I have attached a few preliminary drawings that I’ve prepared for reference.

As you will see, at the intersection of the old garage and the new addition, I will need to incorporate a beam to support a portion of the new roof, and a section of exterior wall. This will be a large beam as it has to span 30’ (client does not want a supporting column in the middle of the garage).

This is a unique situation and as an engineer-in-training I have not yet encountered anything like this yet, so I just want to make sure I’m approaching the situation correctly and taking everything into consideration. I have designed the beam and supporting columns at each end to take into account shear, bending, deflection but my concern here is the lateral stability of the beam / frame. The beam is not laterally supported. I am wondering what type of provisions I should include to ensure the system is stable. Perhaps incorporate a moment frame?

Any help at all would be greatly appreciated.
Thank you.

 

[XR250]

Can you frame a flat ceiling in the existing space to brace the beam?

 

[BAretired]

You need a rigid frame on Gridline 2, and the beam will have to be laterally braced. The wall on Gridline 3 might need a little help for lateral forces too. Perhaps a Simpson strong-wall each side of the overhead door.

 

[DoubleStud]

Since it is a long span beam and more than likely you will have a steel beam, might as well use a steel moment frame. Connect the beam and column as moment connection. You will also have problem with the wall at the garage door. You dont have enough wall to resist lateral load and I dont think you can follow IRC because it is too big. So you will need another moment frame around the garage door.

 

[EV11]

Thank you for the feedback. I will look into Simpson Strong walls to help resist lateral forces at the garage door.

As for the long span beam along gridline 2 - to avoid incorporating a moment frame, I was thinking of adding an interior shear wall (as shown in the attached drawing). The client would be okay with adding this partition. I would then laterally brace the shear wall and column + beam system by securing them both to the existing roof structure. Let me know if you foresee any issues with this approach.

 

[DoubleStud]

Should work. Make sure you calculate the tension force on that shear wall and specify the right strap and anchor on each end of the interior shear wall. You may want to specify plywood on both sides of the studs as opposed to only drywall. Check the nailing on the plywood, may need to be increased.